User's Manual

WiBear11n Data Sheet
Version 1.18
Copyright © 2013 lesswire AG www.lesswire.com Page 16 of 20
Mounting process
The WiBear11n is a surface mount module supplied on a 6-layer FR4-type PCB with gold plated connection
pads and produced in a lead-free process with a lead-free soldering paste. The warpage of the PCB is max.
0,75% according to IPC-A-610E. The thickness of solder resist on the host PCB top side and the WiBear11n
bottom side must be considered for the soldering process.
Modules rated at moisture sensitivity level 3. See moisture sensitive warning label on each shipping bag for
detailed information. After opening the dry pack, modules must be mounted within 168 hours in factory
conditions of maximum 30°C/60%RH or must be stored at less than 10%RH. Modules require baking if the
humidity indicator card shows more than 10% when read at 23±5°C or if the conditions mentioned above are
not met. Please refer to J-STD-033B standard for bake procedure.
Module is compatible with industrial reflow profile for RoHS/Pb-free solders, Sn96.5/Ag3.0/Cu0.5 solder is a
right choice. Use of "No Clean" soldering paste is strongly recommended, cleaning the populated modules is
strongly discouraged - residuals under the module cannot be easily removed with any cleaning process.
Cleaning with water can lead to capillary effects where water is absorbed into the gap between the host board
and module. The combination of soldering flux residuals and encapsulated water could lead to short circuits
between neighboring pads.
Only a single reflow soldering process is permitted for host boards with WiBear11n modules.
The reflow profile used is dependent on the thermal mass of the entire populated PCB, heat transfer efficiency
of the oven and particular type of solder paste used. Since the profile used is process and layout dependent,
the optimum profile should be studied case by case. Recommendations below should be taken as a starting
point guide. In case of basic information necessity please refer to J-STD-020C standard.
Table 16: Recommended reflow profile
Profile feature
Sn-Pb eutectic
(Sn63/Pb37)
RoHS/Pb-free
(Sn96.5/Ag3.0/Cu0.5)
Ramp up rate (T
SMAX
to T
P
) 3°C/sec max 3°C/sec max
Minimum soak temperature (T
SMIN
) 100°C 150°C
Maximum soak temperature (T
SMAX
) 150°C 200°C
Soak time (ts) 60 - 120 sec 60 - 180 sec
Liquidus temperature (T
L
) 183°C 217°C
Time above T
L
(t
L
) 60 - 150 sec 60 - 150 sec
Peak temperature (T
P
) 215 - 225°C 235 - 245°C
Time within +0 / -5°C of actual T
P
(tp) 10 - 30 sec 20 - 40 sec
Ramp down rate 6°C/sec max 6°C/sec max
Time from 25°C to T
P
6 min max 8 min max
Note: lowest value of T
P
and slower ramp down rate (2 - 3°C/sec) is preferred.
Figure 14: Reflow profile